37 research outputs found
A Single-Photon-compatible Telecom-C-Band Quantum Memory in a Hot Atomic Gas
No full textThe efficient storage and on-demand retrieval of quantum optical states that
are compatible with the telecommunications C-band is a requirement for future
terrestrial-based quantum optical networking. Spectrum in the C-band minimises
optical fiber-propagation losses, and broad optical bandwidth facilitates
high-speed networking protocols. Here we report on a telecommunication
wavelength and bandwidth compatible quantum memory. Using the Off-Resonant
Cascaded Absorption protocol in hot Rb vapour, we demonstrate a total
memory efficiency of with a Doppler-limited storage time of
ns. We characterise the memory performance with weak coherent
states, demonstrating signal-to-noise ratios greater than unity for mean photon
number inputs above per pulse
Raman quantum memory with built-in suppression of four-wave-mixing noise
No full textQuantum memories are essential for large-scale quantum information networks. Along with high efficiency, storage lifetime, and optical bandwidth, it is critical that the memory adds negligible noise to the recalled signal. A common source of noise in optical quantum memories is spontaneous four-wave mixing. We develop and implement a technically simple scheme to suppress this noise mechanism by means of quantum interference. Using this scheme with a Raman memory in warm atomic vapor, we demonstrate over an order of magnitude improvement in noise performance. Furthermore we demonstrate a method to quantify the remaining noise contributions and present a route to enable further noise suppression. Our scheme opens the way to quantum demonstrations using a broadband memory, significantly advancing the search for scalable quantum photonic networks
Corrigendum: The longitudinal progression of autonomic dysfunction in Parkinson\u27s disease: a 7-year study (Front. Neurol., (2023), 14, 1155669, 10.3389/fneur.2023.1155669)
No full textCopyright \ua9 2023 Stewart, Ledingham, Foster, Anderson, Sathyanarayana, Galley, Pavese and Pasquini.In the published article, there was an error in the author list as published. The Parkinson\u27s Progression Markers Initiative was erroneously excluded. The author list has now been updated. In addition, an Author\u27s note was missing from the published article. The updated Author\u27s note appears below: Members of Parkinson\u27s Progression Markers Initiative (PPMI) are listed in the Supplementary material. In addition, a Supplementary material file listing the members of The Parkinson\u27s Progression Markers Initiative was erroneously excluded from the publication. The Supplementary material has now been published alongside the original article. In addition there was an error in the Acknowledgments statement as published. The date of data download, the full address of the PPMI database and the RRID number was missing. The updated Acknowledgments statement appears below. Data used in the preparation of this article were obtained on September, 2nd 2022 from the Parkinson\u27s Progression Markers Initiative (PPMI) database (www.ppmi-info.org/access-data-specimens/download-data), RRID:SCR_006431. For up-to-date information on the study, visit www.ppmi-info.org. The authors apologize for these errors and state that this does not change the scientific conclusions of the article in any way. The original article has been updated
High-speed noise-free optical quantum memory
No full textOptical quantum memories are devices that store and recall quantum light and are vital to the realisation of future photonic quantum networks. To date, much effort has been put into improving storage times and efficiencies of such devices to enable long-distance communications. However, less attention has been devoted to building quantum memories which add zero noise to the output. Even small additional noise can render the memory classical by destroying the fragile quantum signatures of the stored light. Therefore noise performance is a critical parameter for all quantum memories. Here we introduce an intrinsically noise-free quantum memory protocol based on two-photon off-resonant cascaded absorption (ORCA). We demonstrate successful storage of GHz-bandwidth heralded single photons in a warm atomic vapour with no added noise; confirmed by the unaltered photon number statistics upon recall. Our ORCA memory meets the stringent noise-requirements for quantum memories whilst combining high-speed and room-temperature operation with technical simplicity, and therefore is immediately applicable to low-latency quantum networks
Spin-wave storage of single photon level light fields in a doped solid
No full textWe present optical storage experiments with weak coherent states and heralded single photons by using the atomic frequency comb technique in the long-lived hyperfine levels in an ensemble of Pr3+ ions doped into a solid.</p
Noise suppression via atomic absorption in a Raman quantum memory
No full textWe demonstrate strong suppression of noise on the output of a Raman quantum memory
Parkinson\u27s, where are we heading?
No full text\ua9 2024 The Author(s). The prevalence of Parkinson’s disease has rapidly increased over the last decade. This editorial discusses our current understanding of the pathophysiological basis for the condition, with a particular focus on the potential role of α-synuclein, and the consequent implications this has for both the development of new investigations and disease-modifying therapies. Specifically, the article discusses the development of a new diagnostic test for cerebrospinal fluid α-synuclein, the development of a new staging system for Parkinson’s disease, which takes into account the α-synuclein, genetic and neuro-imaging status, and the results of two recently completed clinical trials, using monoclonal antibodies wherein α-synuclein is the principal target. We also discuss the increasing awareness of the importance of non-motor symptoms in Parkinson’s disease including hyposmia, rapid eye movement sleep behaviour disorder, and autonomic and cognitive symptoms
K-electron capture to positron emission ratios in allowed transitions
No full textThis thesis describes measurements of the ratios for the K/beta+ ratios for the decays of [30]P and [91]Mo to the ground states of [30]Si and [91]Nb, respectively, and the ft values of the weak transitions to excited states of these nuclei. It also contains a review of all available experimental values of K/beta+ and epsilon/beta[+] ratios for allowed transitions. The work was carried out at the Kelvin Laboratory, University of Glasgow, between October 1969 and October 1973, excluding the period from October 1971 to January 1972. The first chapter contains an introduction to beta decay theory. Orbital electron capture, particularly K-capture, is considered and a theoretical expression given for the ratio of K-electron capture to positron emission for allowed transitions. The following chapter examines the agreement between experimental and theoretical values of the K/beta+ ratio for nuclei with Z ≤ 15. The review of K/beta+ measurements in this region was carried out in collaboration with Ur K. W. D. Ledingham and Dr J. Y. Gourlay. The measurement of the K/beta+ of [30]P ratio described in this chapter was performed by Dr Gourlay and Lr Ledingham together with Dr J. G. Lynch. The present author assisted in the analysis of some of the data. A description of the [30]P experiment is included since it is typical of the low Z K/beta+ measurements and demonstrates the experimental techniques applicable in this region. The experimental K/beta+ ratios for the low Z region are compared with theoretical K/beta+ ratios calculated by the author and Dr Gourlay employing published tables of Fermi functions
